JP6618168B2 - Thin film piezoelectric substrate, thin film piezoelectric element, and manufacturing method thereof - Google Patents

Description

The present invention relates to a thin film-shaped piezoelectric and thin-film piezoelectric substrate on which the electrode is formed, about the thin-film piezoelectric element and its manufacturing how.

  A hard disk device has a large recording capacity and is widely used as the center of a storage device. The hard disk device records and reproduces data with respect to a hard disk (recording medium) by a thin film magnetic head. A component on which the thin film magnetic head is formed is called a head slider, and a component on which the head slider is mounted at the tip is a head gimbal assembly (also referred to as HGA).

  In the hard disk device, the head slider is floated from the surface of the recording medium while rotating the recording medium, thereby recording and reproducing data on the recording medium.

  On the other hand, since the recording density of recording media has increased with the increase in capacity of hard disk drives, it is difficult to control the position of the thin-film magnetic head accurately using only the voice coil motor (hereinafter also referred to as “VCM”). Became. Therefore, conventionally, a technique is known in which an auxiliary actuator (auxiliary actuator) is mounted on the HGA in addition to the main actuator by VCM, and minute position control that cannot be controlled by VCM is performed by the auxiliary actuator.

  The technique for controlling the position of the thin film magnetic head by the main actuator and the auxiliary actuator is also called a two-stage actuator system (dual stage system).

  In the two-stage actuator system, the main actuator rotates the drive arm to position the head slider on a specific track of the recording medium. The auxiliary actuator finely adjusts the position of the head slider so that the position of the thin film magnetic head is optimized.

  Conventionally, a microactuator using a thin film piezoelectric element is known as an auxiliary actuator. The thin film piezoelectric element has a piezoelectric body and a pair of electrode films formed so as to sandwich the piezoelectric body, and each of them is formed in a thin film shape.

Conventionally, as a thin film piezoelectric element, an element using a thin film piezoelectric body made of a ferroelectric material such as lead zirconate titanate ((Pb (Zr, Ti) O ₃ ), hereinafter also referred to as “PZT”). It has been known.

  PZT has a morphotropic boundary (MPB) in the vicinity of the atomic percent ratio of Zr and Ti of 52:48. When the composition of Zr is larger than this, the crystal structure is rhombohedral. It is known to have PZT usually exhibits the highest piezoelectric properties when in this MPB.

  In the conventional thin film piezoelectric element, PZT having a composition near MPB is used, or a piezoelectric layer having a rhombohedral structure and a piezoelectric layer having a tetragonal structure are stacked (for example, Patent Document 1). Etc.).

  In addition, since tetragonal PZT has a large piezoelectricity in the c-axis direction ((001) direction), which is the polarization axis, it is effective to form a piezoelectric body by being oriented in the (001) direction.

  However, when a piezoelectric body made of tetragonal PZT is formed on a silicon substrate, it is easy to form a domain structure in which crystals oriented in the (001) direction and crystals oriented in the (100) direction are mixed. was there. Therefore, in the past, focusing on the fact that this problem is caused by the tensile stress caused by the silicon substrate, an attempt is made to absorb the tensile stress applied to the piezoelectric body by the base layer including an oxide layer having a thermal expansion coefficient close to that of PZT. There was a way of thinking (see, for example, Patent Document 2).

  On the other hand, in rhombohedral PZT, since the polarization axis is in the (111) direction, it is effective to form the piezoelectric body by being oriented in the (111) direction. In this regard, by forming a (111) -oriented rhombohedral PZT thin film on a (111) -oriented Pt film formed on the substrate, the Z crystal of the PZT thin film can be suppressed while suppressing compressive stress with the substrate. It is disclosed that the surface interval of the (222) surface, which is a surface, is made larger than the original surface interval (see, for example, Patent Document 3).

  Furthermore, when crystallized at a high temperature above the Curie point, there is a problem that the PZT crystal is distorted and sufficient piezoelectric characteristics cannot be obtained. In order to solve this, by adding the IIA group element of the periodic table and firing, PZT having excellent piezoelectric characteristics is obtained with c> a for the lattice constants a and c while being rhombohedral. Has also been disclosed (see, for example, Patent Document 4).

JP 2013-258395 A JP 2002-29894 A JP 2004-260994 A JP 2003-133604 A

  By the way, it is desirable that a piezoelectric body made of PZT has stable piezoelectric characteristics with respect to an applied voltage as wide as possible and performs an operation with excellent linearity with respect to an applied voltage as wide as possible.

  However, as disclosed in the above Patent Documents 1 to 4, conventionally, although various devices have been applied to the thin film piezoelectric element so as to improve the piezoelectric characteristics of the piezoelectric body, The range of applied voltage that provides stable piezoelectric characteristics has not been improved. For this reason, there has been a demand for an improvement in which the range of applied voltage in which a stable piezoelectric characteristic can be obtained is wider for a piezoelectric body made of PZT.

Accordingly, the present invention has been made to solve the above-described problems. In the thin film piezoelectric substrate, the thin film piezoelectric element, and the manufacturing method thereof, stable piezoelectric characteristics can be obtained with respect to a wider range of applied voltages, and as much as possible. An object is to perform an operation with excellent linearity with respect to a wide range of applied voltages.

In order to solve the above problems, the present invention provides a thin film piezoelectric substrate in which a laminated film in which a lower electrode film, a piezoelectric film, and an upper electrode film are sequentially laminated is formed on a surface of a film-forming substrate, The upper surface of the body electrode on the upper electrode film side is a concavo-convex surface having a convex portion and a concave portion, and the convex portion is a curved surface protruding in a convex shape from the center surface in the height direction of the concavo-convex surface, and The concave portion is a curved surface that follows the convex portion that is recessed more concavely than the center surface, and an upper electrode film is formed on the concave and convex surface. The piezoelectric film has a general formula Pb (Zr _x , Ti _{(1-x )} ) The following lattice of lead zirconate titanate represented by O ₃ , satisfying the condition of 0.53 <x <0.70 for x, and the lattice constant dv (unit: nm) in the surface vertical direction It conforms to the constant conditions, and (100) plane orientation in the direction perpendicular to the surface. It is formed by,
The piezoelectric film has a tensile stress, the laminated film further includes a stress balancing film laminated on the upper electrode film, and the stress balancing film includes the lower electrode film, the piezoelectric film, and the upper electrode film. It is formed on the upper electrode film so as to have an internal stress that can cancel the element stress that warps in a convex shape in the direction from the upper electrode film to the lower electrode film, and to ensure a balance between the element stress and the internal stress. The upper electrode film has such a thickness that at least a part from the lower surface on the uneven surface side to the upper surface on the stress balancing film side enters the recess, and the upper surface on the stress balancing film side of the upper electrode film is a piezoelectric body. The thin film piezoelectric substrate is characterized by an uneven surface corresponding to the uneven surface of the film and having a stress balancing film formed on the upper surface of the upper electrode film .
dv> 0.02x + 0.398

The present invention also provides a thin film piezoelectric substrate in which a laminated film in which a lower electrode film, a piezoelectric film, and an upper electrode film are laminated in order is formed on the surface of the film-forming substrate, the upper electrode in the piezoelectric film The upper surface on the film side is a concavo-convex surface having a convex portion and a concave portion, and the convex portion is a curved surface that protrudes more convexly than the central surface in the height direction of the concavo-convex surface, and the concave portion is the central surface. a curved surface following the projection portion which is recessed in a concave than, the upper electrode film is formed on its uneven surface, the piezoelectric film, the general formula _{Pb (Zr x, Ti (1} -x)) O 3 It is composed of lead zirconate titanate represented by x, satisfying the condition of 0.53 <x <0.70 for x, and satisfying the following lattice constant condition concerning the lattice constant dv (unit: nm) in the surface vertical direction. Furthermore, it is formed by (100) plane orientation in the surface vertical direction
The piezoelectric film is an epitaxial film formed by epitaxial growth, has a film thickness larger than 3 μm, has a rhombohedral crystal structure, and is formed on an uneven surface of the piezoelectric film. The upper adhesive film provides a thin film piezoelectric substrate having a film thickness that allows at least half of the portion from the lower surface on the uneven surface side to the upper surface on the upper electrode film side to enter the recess.
dv> 0.02x + 0.398

Further, in the case of the thin film piezoelectric substrate, the piezoelectric film is an epitaxial film formed by epitaxial growth, has a film thickness larger than 3 μm, and has a rhombohedral crystal structure. It further has an upper adhesive film formed on the uneven surface, and the upper adhesive film has such a thickness that at least half part from the lower surface on the uneven surface side to the upper surface on the upper electrode film side enters the recess. Is preferred.

In the case of the thin film piezoelectric substrate, the piezoelectric film preferably has a coercive electric field larger than 20V .

The present invention provides a thin film piezoelectric substrate in which a lower electrode film, a piezoelectric film, and an upper electrode film are sequentially laminated, and a laminated film in which a plurality of element portions are formed is formed on the surface of the film formation substrate. The thin film piezoelectric element is manufactured using each element portion after the film-forming substrate is removed from the upper surface of the piezoelectric film on the upper electrode film side. The upper surface of the piezoelectric film is an uneven surface having a convex portion and a concave portion. The convex portion is a curved surface that protrudes in a convex shape from the center surface in the height direction of the concave and convex surface, and the concave portion is a curved surface that follows the convex portion that is concaved from the central surface. The upper electrode film is formed on the concavo-convex surface, and the piezoelectric film is made of lead zirconate titanate represented by the general formula Pb (Zr _x , Ti _(1-x) ) O _3. Satisfying the condition of .53 <x <0.70 and the lattice constant dv ( The upper terminal electrode in which the element portion is connected to the upper electrode film and the lower electrode film are formed by aligning the (100) plane in the direction perpendicular to the surface and conforming to the following lattice constant conditions for nm) and a lower terminal electrode connected,
The piezoelectric film has a tensile stress, the laminated film further includes a stress balancing film laminated on the upper electrode film, and the stress balancing film includes the lower electrode film, the piezoelectric film, and the upper electrode film. It is formed on the upper electrode film so as to have an internal stress that can cancel the element stress that warps in a convex shape in the direction from the upper electrode film to the lower electrode film, and to ensure a balance between the element stress and the internal stress. The upper electrode film has such a thickness that at least a part from the lower surface on the uneven surface side to the upper surface on the stress balancing film side enters the recess, and the upper surface on the stress balancing film side of the upper electrode film is a piezoelectric body. a concave-convex surface corresponding to the uneven surface of the film, to provide a thin-film piezoelectric element stress balancing layer on the upper surface of the upper electrode film is formed.
dv> 0.02x + 0.398

Further, the present invention provides a thin film piezoelectric substrate in which a lower electrode film, a piezoelectric film, and an upper electrode film are sequentially stacked, and a multilayer film in which a plurality of element portions are formed is formed on the surface of the film formation substrate. The thin film piezoelectric element is manufactured using each element portion after the film-forming substrate is removed from the upper surface of the piezoelectric film on the upper electrode film side. The upper surface of the piezoelectric film is an uneven surface having a convex portion and a concave portion. The convex portion is a curved surface that protrudes in a convex shape from the center surface in the height direction of the concave and convex surface, and the concave portion is a curved surface that follows the convex portion that is concaved from the central surface. The upper electrode film is formed on the uneven surface, and the piezoelectric film has a general formula Pb (Zr _x , Ti _(1-x) ) O ₃ And x satisfying the condition of 0.53 <x <0.70 for x and satisfying the following lattice constant conditions regarding the lattice constant dv (unit: nm) in the surface vertical direction And an upper terminal electrode connected to the upper electrode film and a lower terminal electrode connected to the lower electrode film.
The piezoelectric film is an epitaxial film formed by epitaxial growth, has a film thickness larger than 3 μm, has a rhombohedral crystal structure, and is formed on an uneven surface of the piezoelectric film. The upper adhesive film provides a thin film piezoelectric element having a film thickness that allows at least half of the surface from the lower surface on the uneven surface side to the upper surface on the upper electrode film side to enter the recess.
dv> 0.02x + 0.398

In the case of the thin film piezoelectric element, the piezoelectric film is an epitaxial film formed by epitaxial growth, has a film thickness larger than 3 μm, and has a rhombohedral crystal structure. It further has an upper adhesive film formed on the uneven surface, and the upper adhesive film has such a thickness that at least half part from the lower surface on the uneven surface side to the upper surface on the upper electrode film side enters the recess. Is preferred.

In the case of the thin film piezoelectric element, the piezoelectric film preferably has a coercive electric field larger than 20V .

And this invention performs the etching with respect to the laminated film formation process in which the laminated film in which the lower electrode film, the piezoelectric film, and the upper electrode film were laminated in order is formed on the surface of a plurality of deposition substrates, and the laminated film An element portion forming step for forming a plurality of element portions in the laminated film, and an electrode forming step for forming a lower terminal electrode and an upper terminal electrode on the lower electrode film and the upper electrode film in each element portion, respectively. The laminated film forming step includes a measuring step of measuring a diffraction angle of a diffraction intensity peak on the (002) plane by an X-ray diffraction method for a plurality of film forming substrates, and among the plurality of film forming substrates, A thin film piezoelectric element is manufactured using a lattice constant condition-compatible substrate that meets the following lattice constant condition relating to the lattice constant dv (unit: nm) in the surface vertical direction obtained based on the diffraction angle obtained by the measurement process. Thin film To provide a method of manufacturing a conductor element.
dv> 0.02x + 0.398

  In the above manufacturing method, an insulating substrate manufacturing process for manufacturing an insulating substrate having an insulating film formed on the surface of the substrate, and a deposition substrate and an insulating substrate are laminated so that the insulating film and the upper electrode film face each other. And a substrate removal step of removing either the insulating substrate or the film-forming substrate from among the laminated substrates laminated by the substrate lamination step, and the element after the substrate removal step is executed. It is preferable to perform a part formation process.

As described above in detail, according to the present invention, the thin film piezoelectric substrate, Te thin film piezoelectric element and its manufacturing method odor, more stable piezoelectric characteristic is obtained over a wide range of applied voltage, applied as wide a range as possible An operation having excellent linearity with respect to the voltage can be performed.

(A) is a perspective view showing the whole thin film piezoelectric substrate, (b) is an enlarged plan view of the surface of the thin film piezoelectric substrate after the element portion is formed. FIG. 2 is a sectional view taken along line 2-2 of FIG. It is the top view to which the principal part of the 1st surface after an element part was formed was expanded. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. FIG. 5 is a sectional view taken along line 5-5 of FIG. It is sectional drawing to which the part from the piezoelectric film of a thin film piezoelectric element to a stress balance film was expanded. It is the sectional drawing which expanded the piezoelectric material film similarly. It is sectional drawing to which the principal part of FIG. 6 was expanded. It is sectional drawing which shows the manufacturing process of the thin film piezoelectric element which concerns on embodiment of this invention. FIG. 10 is a cross-sectional view showing a manufacturing step subsequent to FIG. 9. FIG. 11 is a cross-sectional view showing a manufacturing step subsequent to FIG. 10. (A) is sectional drawing which shows the subsequent manufacturing process of FIG. 11, (b) is sectional drawing which shows the subsequent manufacturing process of (a). (A) is sectional drawing which shows the subsequent manufacturing process of FIG.12 (b), (b) is sectional drawing which shows the subsequent manufacturing process of (a). (A) is a graph showing the correspondence between the diffraction angle of the diffraction intensity peak obtained by XRD and the coercive electric field (negative side) for eight thin film piezoelectric substrates, and (b) shows a large coercive electric field with a lattice constant dv. It is a graph which shows the correspondence of the threshold value when becoming and x in lattice constant conditions. It is the perspective view which looked at the whole HGA relevant to this invention from the front side. It is the perspective view which looked at the principal part of HGA of FIG. 15 from the front side. It is the perspective view which looked at the principal part of the suspension which comprises HGA of FIG. 15 from the front side. It is the perspective view which expanded and showed the part to which the thin film piezoelectric element of a flexure was fixed. It is a perspective view which shows the hard disk drive provided with HGA relevant to this invention. 1 is a cross-sectional view illustrating a schematic configuration of an inkjet head related to the present invention. It is the top view which showed the structure of the outline of the variable focus lens relevant to this invention. FIG. 22 is a cross-sectional view taken along line 22-22 of FIG. It is sectional drawing which showed the structure of the outline of the variable focus lens concerning a modification. It is sectional drawing which showed the structure of the outline of the pulse wave sensor relevant to this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is used for the same element and the overlapping description is abbreviate | omitted.

(Structure of thin film piezoelectric substrate)
First, the structure of the thin film piezoelectric substrate 1 according to the embodiment of the present invention will be described with reference to FIGS.

  1A is a perspective view showing the entire thin film piezoelectric substrate 1, and FIG. 1B is an enlarged plan view of the surface of the thin film piezoelectric substrate 1 after the element portion 10 is formed. is there. 2 is a cross-sectional view taken along line 2-2 of FIG. 1B, FIG. 3 is an enlarged plan view of the main part of the first surface 1a after the element portion 10 is formed, and FIG. It is a 4-line sectional view.

  A thin film piezoelectric substrate 1 is a thin film piezoelectric substrate according to an embodiment of the present invention, and is configured using a silicon wafer 2 as a film forming substrate. As shown in FIG. 1A, the thin film piezoelectric substrate 1 has a laminated film 3 formed on the first surface 1a of the silicon wafer 2 (the back surface side of the first surface 1a is the second surface 1b). . In the thin film piezoelectric substrate 1 according to the embodiment of the present invention, a plurality of element portions 10 are formed when a plurality of element portions 10 to be described later are not formed in the laminated film 3 (FIG. 1A). (FIG. 1B).

  As shown in FIG. 2, the laminated film 3 includes a base film 15, a lower electrode film 17, a lower adhesion film 16 a, a piezoelectric film 13, an upper adhesion film 16 b, an upper electrode film 27 and a stress balancing film 14 which will be described later. It has a laminated structure in which a plurality of thin films are laminated. 2 includes the stress balancing film 14, the stacked film 3 may not include the stress balancing film 14.

  A plurality of element portions 10 can be formed in the laminated film 3 as shown in FIG. The plurality of element portions 10 are separated from each other via a gap portion 11, and are regularly arranged in the vertical direction and the horizontal direction. Each element unit 10 forms a thin film piezoelectric element 12b described later.

  As shown in FIG. 3, each element portion 10 is formed in a generally rectangular shape in plan view. A lower terminal electrode 19a, an upper terminal electrode 19b, and a contact hole 21 are formed on one end side of each element portion 10 in the longitudinal direction. As shown in FIG. 4, the contact hole 21 is a hole that reaches the surface of the lower electrode film 17 through the upper adhesive film 16b, the piezoelectric film 13 and the lower adhesive film 16a, and has a lower terminal inside the hole. An electrode 19a is formed. The bottom of the lower terminal electrode 19a is directly connected on the surface of the lower electrode film 17. The upper terminal electrode 19 b is disposed inside the through hole 14 a of the stress balancing film 14 and is formed directly on the surface of the upper electrode film 27. Although not shown, an insulating film made of polyimide or the like may be formed on the upper terminal electrode 19b so as to cover the element portion 10. In that case, by forming through holes in the insulating film, the lower electrode film 17 and the lower terminal electrode 19a, and the upper electrode film 27 and the upper terminal electrode 19b can be brought into contact with each other.

(Structure of thin film piezoelectric element)
Next, the structure of the thin film piezoelectric element will be described with reference to FIGS. Here, FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 18 showing an enlarged portion where a thin film piezoelectric element 12b of a flexure 106 described later is fixed. FIG. 6 is an enlarged cross-sectional view of a portion from a piezoelectric film 13 (described later) to a stress balancing film 14 in the thin film piezoelectric element 12b fixed to the flexure 106, and FIG. FIG. 8 is an enlarged cross-sectional view, and FIG. 8 is an enlarged cross-sectional view of the main part of FIG. 6, 7, and 8 are illustrated with emphasis on the unevenness of each film for the convenience of illustration.

  The thin film piezoelectric element 12b (the same applies to the thin film piezoelectric element 12a) is fixed to a flexure 106 of the HGA 101 described later. The thin film piezoelectric element 12b is manufactured using the above-described thin film piezoelectric substrate 1 (thin film piezoelectric substrate 1 on which a plurality of element portions 10 are formed). By using each element portion 10 after the silicon wafer 2 is removed from the thin film piezoelectric substrate 1, thin film piezoelectric elements 12b and 12a are formed.

  As shown in FIG. 5, the thin film piezoelectric element 12b (the same applies to the thin film piezoelectric element 12a) includes the base film 15, the lower electrode film 17, the lower adhesion film 16a, the piezoelectric film 13, and the upper adhesion. The film 16b, the upper electrode film 27, and the stress balancing film 14 are included and have a stacked structure in which these are stacked in order. In the thin film piezoelectric element 12b, the stress balancing film 14 is formed on the upper electrode film 27 so that a balance between an element stress F12 and an internal stress F14, which will be described later, is ensured. The thin film piezoelectric elements 12b and 12a are fixed to the surface of the base insulating layer 5 described later using an epoxy resin (not shown). In the thin film piezoelectric element 12b of FIG. 5, the stress balancing film 14 is formed as a preferred embodiment, but the thin film piezoelectric element 12b may not have the stress balancing film 14 formed thereon.

  The “upper part” and “lower part” in the present invention do not necessarily indicate the upper side and the lower side of the state in which the thin film piezoelectric element is fixed on the base insulating layer 5. These are terms for convenience used to distinguish between two electrode films facing each other across the piezoelectric film 13. In an actual product, the upper electrode film 27 and the upper adhesion film 16b may be disposed on the lower side, and the lower electrode film 17 and the lower adhesion film 16a may be disposed on the upper side.

The piezoelectric film 13 is formed in a thin film shape using a piezoelectric material made of lead zirconate titanate (hereinafter also referred to as “PZT”) represented by the general formula Pb (Zr _x , Ti _(1-x) ) O _3. Has been. The piezoelectric film 13 is formed by epitaxial growth and has a thickness of about 1 μm to 5 μm. The piezoelectric film 13 preferably has a film thickness larger than 3 μm and has a rhombohedral crystal structure. In rhombohedral crystals, the lattice constants of the a-axis, b-axis, and c-axis of the crystal lattice are equal. While the piezoelectric film 13 according to the present invention has such a rhombohedral crystal structure, the lattice constant dv in the direction perpendicular to the film surface meets the lattice constant condition described later. The piezoelectric film 13 has a tensile stress of about 5 MPa to 50 MPa (preferably 5 MPa to 20 MPa).

  The piezoelectric film 13 according to the present embodiment has 0.53 <in the general formula “x” (x is an atomic percentage of Zr in PZT and is also referred to as “Zr composition ratio” in the present embodiment). It meets the condition of x <0.70. The piezoelectric film 13 is formed by being oriented in the (100) plane direction perpendicular to the surface thereof. Furthermore, when the Zr composition ratio x is 0.55, the piezoelectric film 13 conforms to a peak condition described later, and when the Zr composition ratio x is different from 0.55, the piezoelectric film 13 satisfies the lattice constant condition described later. It fits.

  In the present embodiment, as shown in FIGS. 6 and 7, the piezoelectric film 13 has an uneven surface 13 </ b> A on the surface (also referred to as an upper surface) on the upper electrode film 27 side. The uneven surface 13A has a plurality of convex portions 13a and concave portions 13b that are both curved. As for uneven surface 13A, each convex part 13a and recessed part 13b are alternately arrange | positioned along uneven surface 13A, and the cross-sectional shape is a waveform. Each convex portion 13a and concave portion 13b are curved surfaces that are gently inclined, but in this embodiment, a portion that protrudes outwardly from the central surface 13L in the height direction of the concave and convex surface 13A is a convex portion. The inner part following 13a and the convex part 13a which became depressed more concavely than the center surface 13L is the recessed part 13b.

Incidentally, the piezoelectric film 13 which is shown as a preferred embodiment, and have a concave-convex surface 13A.

  Further, as shown in FIG. 8, the uneven surface 13A has a difference in height (also referred to as surface roughness) between the convex portion 13a and the concave portion 13b as t13. Then, the film thickness t16b (about 35 nm) of the upper adhesion film 16b described later is approximately the same or somewhat larger than the surface roughness t13. It suffices that at least half of the upper adhesive film 16b from the lower surface to the upper surface enters the recess 13b, and almost the whole may enter as shown in FIG. Thereby, as shown in FIG. 6, the upper adhesive film 16b has an uneven structure corresponding to the uneven surface 13A of the piezoelectric film 13, and the upper surface of the upper adhesive film 16b becomes an uneven surface corresponding to the uneven surface 13A. In this case, the upper surface of the upper adhesive film 16b has a convex portion and a concave portion corresponding to the concave and convex surface 13A.

  The film thickness t27 of the upper electrode film 27 to be described later is such that at least a part from the lower surface (surface on the uneven surface 13A side) to the upper surface (surface on the stress balancing film 14 side) of the upper electrode film 27 is the recess 13b. The size is enough to get inside. Since the film thickness t27 is such a size, the upper electrode film 27 also has an uneven structure corresponding to the uneven surface 13A of the piezoelectric film 13, and the upper surface thereof is an uneven surface corresponding to the uneven surface 13A. Yes. Furthermore, the film thickness t14 (about 100 nm) of the stress balancing film 14 described later is larger than the film thickness t27 (t27 <t14).

  The base film 15 is formed using a nitride such as zirconium oxide, yttrium oxide, magnesium oxide, rare earth element oxide, or titanium nitride. The base film 15 shown in FIG. 5 has a first base film 15a and a second base film 15b, and a two-layer structure in which the second base film 15b is stacked on the first base film 15a. However, it does not have to have a two-layer structure.

The lower electrode film 17 is, for example, a thin film (having a film thickness of about 100 nm) made of a metal material containing Pt as a main component (may contain Au, Ag, Pd, Ir, Ru, Cu in addition to Pt). And formed on the base film 15. The crystal structure of the lower electrode film 17 is a face-centered cubic structure. The lower adhesion film 16a is a thin film (having a thickness of about 20 nm) made of an epitaxially grown conductive material such as SrRuO ₃ (also referred to as SRO), and is formed on the upper surface of the lower electrode film 17 on the piezoelectric film 13 side. Has been. A piezoelectric film 13 is formed on the lower adhesion film 16a.

The upper adhesion film 16b is a thin film (having a film thickness of about 35 nm) made of an amorphous conductive material such as SrRuO ₃ , and is formed on the uneven surface 13A of the piezoelectric film 13. As described above, the upper surface of the upper adhesive film 16b is an uneven surface corresponding to the uneven surface 13A.

  The upper electrode film 27 is made of a polycrystalline material using, for example, a metal material containing Pt as a main component (may contain Au, Ag, Pd, Ir, Rh, Ni, Pb, Ru, Cu in addition to Pt). It is a thin film (film thickness is about 50 nm), and is formed on the upper adhesion film 16b. As described above, the upper surface of the upper electrode film 27 is also an uneven surface corresponding to the uneven surface 13A. The crystal structure is a face-centered cubic structure.

  The stress balancing film 14 is formed on the upper electrode film 27. The stress balancing film 14 is a polycrystalline thin film (thickness is about 100 nm) using an alloy material, and has an internal stress F14 that can cancel (cancel) an element stress F12 described later.

  The stress balancing film 14 is formed using, for example, an alloy material mainly composed of iron (Fe). The crystal structure of the stress balancing film 14 is preferably a body-centered cubic structure. The stress balancing film 14 is made of, for example, Fe, Co, Mo, Au, Pt, Al, Cu, Ag, Ta, Cr, Ti, Ni, Ir, Nb, Rb, Cs, Ba, V, W, Ru. It is preferable to use an alloy material containing at least one of them. The stress balancing film 14 is more preferably made of an alloy material containing Fe and Co and Mo.

  Here, the element stress F12 is the direction in which the lower electrode film 17, the piezoelectric film 13 and the upper electrode film 27 are directed from the upper electrode film 27 toward the lower electrode film 17 in the thin film piezoelectric element 12b (downward in FIG. 5). It is the stress that tries to bend in a convex shape. The internal stress F14 is a stress that the stress balancing film 14 has, and acts to spread the stress balancing film 14 outward and to warp it upward.

  When the stress balancing film 14 having this compressive stress is formed on the upper electrode film 27, the internal stress F14 acts so as to cancel the element stress F12, and the stress balance is ensured. The internal stress F14 is a stress in which both the stress F14a caused by the material forming the stress balancing film 14 and the stress F14b caused by crystal grain growth of the stress balancing film 14 are applied.

  The above-described upper terminal electrode 19b and lower terminal electrode 19a are directly formed on the surfaces of the upper electrode film 27 and the lower electrode film 17, respectively. The upper terminal electrode 19b and the lower terminal electrode 19a are connected to a connection wiring 111 described later through electrode pads 118a and 118b described later.

  The protective insulating layer 25 is formed so as to cover the entire surface of the thin film piezoelectric element 12a and the thin film piezoelectric element 12b. The protective insulating layer 25 is formed using polyimide, for example, and has a thickness of about 1 μm to 10 μm. When the thin film piezoelectric elements 12 a and 12 b have a protective insulating layer in advance, the thin film piezoelectric elements 12 a and 12 b may not be covered with the protective insulating layer 25.

  The crystallinity of the upper electrode film 27 and the lower electrode film 17 is preferably different. The lower electrode film 17 is preferably a conductive thin film formed by epitaxial growth (such a thin film is also referred to as an “epitaxial film”), and the upper electrode film 27 can be a conductive thin film that is not epitaxially grown. More preferably, the lower electrode film 17 may be a Pt thin film formed by epitaxial growth, and the upper electrode film 27 may be a polycrystalline conductor thin film.

  Each crystallinity can be easily examined by measuring a rocking curve by an X-ray diffraction method. In the epitaxial film of the lower electrode film 17, it is preferable that the half width of the rocking curve is narrower than 1 degree. Further, in the epitaxial film, it is preferable that the peak intensity of the other plane is 1/10 or less, more preferably only the peak of the alignment plane is observed with respect to the peak intensity of the alignment plane in the θ-2θ measurement.

  On the other hand, the metal thin film used for the upper electrode film 27 has a half-width of the rocking curve larger than that of the lower electrode film 17 and is usually larger than 1 degree. Moreover, peaks from a plurality of plane orientations are also observed in the θ-2θ measurement. Further, the upper electrode film 27 may be an amorphous film. In an amorphous film, a clear peak does not appear in either θ-2θ measurement or rocking curve measurement. Crystallinity can be easily determined from a diffraction image observed with a transmission electron microscope. In the epitaxial film, a clear pattern with the same spot arrangement is observed regardless of the location in the film, but in a polycrystalline film that is not an epitaxial film, the orientation and interval of the spot arrangement differs depending on the location, A diffraction image in which a plurality of spot patterns overlap is observed. In addition, a clear diffraction pattern cannot be obtained with an amorphous film.

(Thin Film Piezoelectric Substrate and Thin Film Piezoelectric Element Manufacturing Method)
Next, a method for manufacturing the thin film piezoelectric substrate 1 and the thin film piezoelectric element 12b will be described with reference to FIGS. The thin film piezoelectric substrate 1 and the thin film piezoelectric element 12b (the same applies to the thin film piezoelectric element 12a) are manufactured as follows.

  First, the thin film piezoelectric substrate 1 is manufactured by executing a substrate manufacturing process. In the substrate manufacturing process, a plurality of silicon wafers 2 (thickness is about 400 to 600 μm, diameter is about 100 to 200 mm) are prepared, and the laminated film 3 is formed on the first surface 1a thereof, whereby the thin film piezoelectric substrate 1 Is manufactured. The substrate manufacturing process includes a laminated film forming process for forming the laminated film 3. The laminated film forming step includes a piezoelectric film forming step described later.

  In the laminated film forming step, the piezoelectric film 13 is formed by controlling a first film formation parameter described later in the piezoelectric film forming step.

When the laminated film forming step is started, first, a base oxide film 15 is formed by epitaxially growing a metal oxide thin film such as ZrO ₂ . The base film 15 may be a single layer or may be formed by stacking a plurality of layers as shown in FIG. As the base film 15, a ZrO ₂ film, a rare earth element oxide film of yttrium-containing rare earth element and oxygen, or a mixture or laminated film thereof can be preferably used.

  Subsequently, a lower electrode film forming step is performed. In this step, a metal material containing Pt as a main component is epitaxially grown on the base film 15 by sputtering. The lower electrode film 17 is formed by this epitaxial growth. Next, a lower adhesion film forming step is performed. In this step, the lower adhesion film 16a is formed on the upper surface of the lower electrode film 17 by sputtering using, for example, SRO.

  Thereafter, a piezoelectric film forming step is executed. In this step, as shown in FIG. 10, a piezoelectric material made of PZT is epitaxially grown on the lower adhesion film 16a by sputtering. At this time, the piezoelectric film 13 is formed by controlling the first film formation parameter.

  In this step, a plurality of piezoelectric films 13 having different ratios of Zr and Ti and interplanar spacing in the direction perpendicular to the surface of the piezoelectric film 13 are formed. This point will be described in detail in a later embodiment.

  Here, the first film formation parameters are various parameters adjusted when the piezoelectric film 13 is formed by sputtering, and at least the film formation speed, the substrate temperature, the gas pressure, and the gas composition. It is included. The numerical value of the first film formation parameter when the uneven surface 13A is formed can be set as the first piezoelectric film formation condition.

As a result of various experiments, the inventor of the present application, in the case where a PZT film is epitaxially grown by sputtering on the epitaxial film in which the base film, the lower electrode film, and the lower adhesion film are stacked on the silicon wafer 2, is described below. By forming a PZT film with a combination of numerical values appropriately selected from the body film formation conditions, a plurality of piezoelectric films 13 having different plane spacings in the direction perpendicular to the surface were formed at the respective ratios of Zr and Ti.
First piezoelectric film forming conditions Film forming speed is about 0.1 to 3 μm / h, substrate temperature is about 350 to 750 ° C., gas pressure is about 0.01 to 10 Pa, gas composition is oxygen partial pressure 1 to The mixed gas of argon and oxygen is about 10%.

  Therefore, in the piezoelectric film forming step, by controlling the first film formation parameter so as to satisfy the first piezoelectric film formation condition, the surface spacing in the direction perpendicular to the surface is obtained at each ratio of Zr and Ti. A plurality of piezoelectric films 13 having different values can be formed.

  In addition, the piezoelectric film forming step can be performed as follows. In this case, a piezoelectric material made of PZT is epitaxially grown on the lower adhesion film 16a by a sol-gel method. At this time, by controlling the second film formation parameter, a plurality of piezoelectric films 13 having different surface intervals in the direction perpendicular to the surface are formed.

  Also in this case, a plurality of piezoelectric films 13 are formed. In each piezoelectric film 13, the surface spacing in the direction perpendicular to the surface differs in the ratio of Zr and Ti.

  The second film formation parameters are various parameters that are adjusted when the piezoelectric film 13 is formed by the sol-gel method. At least the spin coating rotation speed, the drying temperature, the prebake temperature, and the pressure annealing are performed. Includes oxygen pressure and temperature.

As a result of various experiments, the inventor of the present application, in the case where the PZT film is epitaxially grown by the sol-gel method on the epitaxial film in which the base film, the lower electrode film, and the lower adhesion film are stacked on the silicon wafer 2, the following second It has been found that by forming a PZT film under a combination of conditions appropriately selected from the piezoelectric film forming conditions, a plurality of piezoelectric films 13 having different surface intervals in the direction perpendicular to the surface are formed.
Second piezoelectric film forming conditions Spin coating rotation speed is about 3000 to 5000 rpm, drying temperature is about 200 to 300 ° C. (in oxygen), pre-baking temperature is about 400 to 500 ° C. (in oxygen), oxygen pressure of pressure annealing And temperature shall be about 3-10 atmospheres and about 600-800 degreeC.

  Subsequently, an upper adhesion film forming step is performed. In this step, as shown in FIG. 11, the upper adhesion film 16b is formed on the uneven surface 13A of the piezoelectric film 13 by sputtering using, for example, SRO.

  Subsequently, an upper electrode film forming step is performed. In this step, a metal material containing Pt as a main component is grown on the upper adhesion film 16b by sputtering, and the upper electrode film 27 is formed. The upper electrode film is not an epitaxially grown film, but a polycrystalline non-oriented film or a preferentially oriented film of (110) plane or (111) plane.

  As described above, the lower adhesive film forming step and the upper adhesive film forming step are performed, so that the piezoelectric film 13 and the upper electrode film 27 are interposed through the lower adhesive film 16a and the upper adhesive film 16b, respectively. The lower electrode film 17 and the piezoelectric film 13 are stacked.

  Thereafter, a stress balancing film forming step may be performed. In this step, the stress balancing film 14 is formed by sputtering using an alloy material containing iron (Fe) as a main component (for example, an alloy material containing Fe, Co, and Mo).

  Then, although an element part formation process is performed, an insulating substrate manufacturing process, a board | substrate lamination process, and a board | substrate removal process may be performed prior to an element part formation process. By doing so, the stress generated between the piezoelectric film 13 and the silicon wafer 2 can be released in the manufacturing stage.

In the insulating substrate manufacturing process, an insulating wafer 26 is manufactured by forming an insulating film 23 made of silicon oxide (SiO ₂ ) on the surface of a silicon wafer 22 similar to the silicon wafer 2 as shown in FIG.

  Subsequently, a substrate lamination process is performed. In this step, as shown in FIG. 12B, the thin film piezoelectric substrate 1 and the insulating wafer 26 are bonded using an insulating resin such as an epoxy resin while the insulating film 23 and the laminated film 3 face each other. Thus, the thin film piezoelectric substrate 1 and the insulating wafer 26 are laminated with the insulating resin layer 24 interposed therebetween.

  Thereafter, a substrate removal process is performed. In this step, either the silicon wafer 2 or the silicon wafer 22 is removed from the thin film piezoelectric substrate 1 and the insulating wafer 26 (which correspond to the laminated substrate) laminated in the substrate laminating step. In the present embodiment, as shown in FIG. 13A, the silicon wafer 2 is left and the silicon wafer 22 is removed by etching or the like.

  Then, an element part formation process is performed. In this step, as shown in FIG. 13A, a photoresist is applied to the surface of the insulating film 23 and then patterned using a predetermined photomask to form a resist pattern 28. Thereafter, etching is performed on the insulating film 23, the insulating resin layer 24, and the laminated film 3 using the resist pattern 28 as a mask, and unnecessary portions thereof are removed. Then, the laminated film 3 is divided into a plurality of individual regions 3 a through the gaps 11. The element portion 10 described later is formed by each individual region 3a.

  Furthermore, after the insulating film 23 and the insulating resin 24 are removed from the surface of the remaining laminated film 3, an electrode forming process described later is performed. Thereafter, a protective insulating layer 25 made of polyimide is formed on each individual region 3a, and a plurality of element portions 10 are formed on the surface of the silicon wafer 2 as shown in FIG.

  In the electrode forming step, the protective insulating layer 25 and the stress balancing film 14 are removed by etching to form the through hole 14a, and the piezoelectric film 13 and the like are removed to form the contact hole 21. Further, a lower terminal electrode 19a and an upper terminal electrode 19b are formed on the lower electrode film 17 and the upper electrode film 27 by plating or the like, respectively. Thus, the thin film piezoelectric substrate 1 shown in FIGS. 1 and 2 is manufactured.

  When the silicon wafer 2 is removed from the thin film piezoelectric substrate 1 manufactured as described above by etching or the like, a plurality of thin film piezoelectric elements 12b are formed. The formed thin film piezoelectric element 12b is fixed to the surface of the base insulating layer 5 in the HGA 101, for example.

(Example)
As described above, in the present embodiment, the piezoelectric film 13 is formed in a plurality of patterns in the laminated film forming step. The inventor of the present application forms the piezoelectric film 13 by appropriately adjusting the above-described piezoelectric film forming conditions (first piezoelectric film forming conditions or second piezoelectric film forming conditions), and the direction perpendicular to the surface A total of eight thin film piezoelectric substrates 1 having piezoelectric films 13 having different surface intervals were manufactured. In these thin film piezoelectric substrates 1, the piezoelectric film 13 is formed so that the ratio (atomic%) of Zr and Ti is 55:45. In each thin film piezoelectric substrate 1, the ratio ratio of Zr and Ti is measured according to X-ray fluorescence spectroscopy (XRF). As a result, it has been confirmed that the ratio of Zr to Ti is 55:45.

  The diffraction angle of the diffraction intensity peak on the PZT (002) plane of the eight manufactured thin film piezoelectric substrates 1 is determined by an X-ray diffraction method (X-ray Diffraction, “θ-2θ method using Cu-Kα rays”). XRD "(also referred to as" measurement process "). Subsequently, the upper electrode film 27, the upper adhesion film 16b, the piezoelectric film 13, the lower adhesion film 16a and the lower electrode film 17 are patterned by etching, and further, the upper terminal electrode 19b and the lower terminal electrode 19a are formed. The coercive electric field of the piezoelectric film 13 was obtained by measuring the polarization-voltage curve.

  FIG. 14A shows a correspondence relationship between the investigated diffraction angle and the coercive electric field (absolute value on the negative side, the unit is V). In FIG. 14A, the horizontal axis indicates the diffraction angle of the diffraction intensity peak on the (002) plane, and the vertical axis indicates the coercive electric field (absolute value on the negative side, the unit is V) in the polarization-voltage curve. FIG. 14A shows eight measurement points, and each measurement point corresponds to each of the laminated films 3 having eight patterns.

  The diffraction angle and the coercive electric field (negative side) do not show a certain correspondence. However, as shown in FIG. 14A, when the diffraction angle is smaller than 44.25 degrees (4 patterns out of 8 patterns), the absolute value of the coercive electric field (Vc−) is larger than in other cases. large. When the diffraction angle is smaller than 44.25 degrees, the absolute value of the coercive electric field (Vc−) is about “22” to “20” V, which is larger than “20” V. This is because it is only about "18" to "17" V.

  The coercive electric field (Vc−) is a voltage at which polarization inversion occurs when an electric field in a direction opposite to the polarization direction is applied to the piezoelectric body. The piezoelectric body is deformed in accordance with the applied voltage until the applied voltage reaches this voltage (coercive electric field), but when the coercive electric field is exceeded, the amount of deformation rapidly decreases. Therefore, the piezoelectric body has a wider range of applied voltages that can be deformed as the absolute value of the coercive electric field (Vc−) is larger. Therefore, such a piezoelectric body exhibits a stable piezoelectric characteristic with respect to a wider range of applied voltages and becomes a preferable piezoelectric body that performs an operation with excellent linearity with respect to a wider range of applied voltages.

  That the diffraction angle of the diffraction intensity peak on the (002) plane is smaller than 44.25 degrees is also referred to as a peak condition, and the thin film piezoelectric substrate 1 that conforms to the peak condition is also referred to as a peak condition compatible substrate.

  When the peak condition compatible substrate is used, more preferable thin film piezoelectric elements 12b can be manufactured than when the other thin film piezoelectric substrate 1 is used. “Preferable in this case” means that a stable piezoelectric characteristic is exhibited with respect to a wider range of applied voltages and an operation with excellent linearity is performed with respect to a wider range of applied voltages.

  On the other hand, in addition to the case where the ratio of Zr and Ti is 55:45, the inventor of the present application performs the same measurement as above for the laminated film 3 having a composition of x> 0.53 in which PZT is rhombohedral. Based on the diffraction angle, the threshold value when the coercive electric field (Vc−) of dv (lattice constant in the direction perpendicular to the surface of the piezoelectric film 13 and the unit is nm) increases was obtained. The result is as shown in FIG. In FIG. 14B, the horizontal axis is x (x is the ratio of Zr atoms out of the number of Zr and Ti atoms), and the vertical axis is the threshold value of dv when the coercive electric field increases.

Then, when dv is larger than 0.02x + 0.398, that is, when dv> 0.02x + 0.398 (which corresponds to the upper side of the dotted line in FIG. 14B), the case is not so It was confirmed that the absolute value of the coercive electric field (Vc−) is larger than (when dv is 0.02x + 0.398 or less). The range of x where such an effect was obtained was 0.53 <x <0.70. When x exceeds 0.70, the piezoelectricity is significantly reduced due to the composition being far from the MPB, so that a sufficient coercive electric field cannot be obtained regardless of the magnitude of dv. In the present embodiment, when the condition of 0.53 <x <0.70 is satisfied, the following relational expression regarding the lattice constant dv is also referred to as a lattice constant condition.
dv> 0.02x + 0.398

  Therefore, when 0.53 <x <0.70 and x is a value different from 0.55, the thin film piezoelectric substrate 1 (also referred to as a lattice constant condition compatible substrate) that conforms to the lattice constant condition is used. More preferable thin film piezoelectric elements 12b can be manufactured.

  When x is 0.55, the value on the right side of the above lattice constant condition is 0.409 (= 0.02 × 0.55 + 0.398). This is the lattice when x is 0.55. It is smaller than a constant (0.417). Therefore, even when x is 0.55, a substrate having a lattice constant condition can be used.

  In any of the above cases, methods such as EPMA, EDS, Auger spectroscopy and the like can be used in addition to XRF to measure the Zr / Ti ratio. In addition to the XRD method using the Cu—Kα ray described above, the XRD method using synchrotron radiation, a transmission electron microscope (TEM), or the like can be used for the measurement of the surface spacing.

(Effects of thin film piezoelectric substrate and thin film piezoelectric element)
As described above, in the thin film piezoelectric substrate 1 according to the present embodiment, when 0.53 <x <0.70 and when the lattice constant condition is satisfied, it is more than when the lattice constant condition is not satisfied. However, the absolute value of the coercive electric field (Vc−) increases. This includes the case where x is 0.55.

  Therefore, in 0.53 <x <0.70, it is preferable to use a substrate having a lattice constant condition, which is preferable to using a thin film piezoelectric substrate that is not so, that is, a stable piezoelectric with respect to a wider range of applied voltages. Many thin film piezoelectric elements 12b exhibiting characteristics and performing operations with excellent linearity with respect to a wider range of applied voltages can be manufactured. In addition, the thin film piezoelectric element 12b manufactured using the lattice constant condition compatible substrate is a preferable element.

  Moreover, the thin film piezoelectric substrate 1 can form a plurality of element portions 10 in the laminated film 3. In that case, since each element part 10 has the upper terminal electrode 19a and the lower terminal electrode 19b, by removing the silicon wafer 2, a plurality of preferable thin film piezoelectric elements 12b can be manufactured.

  Furthermore, since the piezoelectric film 13 has a tensile stress, it is possible to ensure a stress balance in each thin film piezoelectric element 12b. Since the piezoelectric film 13 is an epitaxial film formed by epitaxial growth, the crystal axes are aligned in all three directions of the a-axis, b-axis, and c-axis. Since the piezoelectric film 13 has a film thickness larger than 3 μm, the amount of displacement of the thin film piezoelectric element 12b can be increased.

  The piezoelectric film 13 has a rhombohedral crystal structure. However, in the rhombohedral crystal, since the lattice constants of all of the a-axis, b-axis, and c-axis are equal, domain formation does not occur even during the cooling process. . In XRD, a peak having two maximum values is not observed. The piezoelectric film 13 made of such rhombohedral PZT is oriented in the (100) direction (surface vertical direction), not in the (111) direction which is the polarization axis, and the plane spacing in the (100) direction is as described above. By doing so, a preferable thin film piezoelectric substrate 1 can be obtained.

  On the other hand, the thin film piezoelectric element 12b includes the piezoelectric film 13 and the stress balancing film 14, and thus has the following effects. That is, the upper adhesive film 16b is formed on the uneven surface 13A of the piezoelectric film 13, but the film thickness is very small, and the upper surface is the same uneven surface as the uneven surface 13A. Therefore, the upper electrode film 27 formed on the upper adhesion film 16b has an internal stress that becomes a compressive stress.

  Further, since the upper surface of the upper electrode film 27 is also an uneven surface similar to the uneven surface 13A, the stress balancing film 14 also has a stress F14b that becomes a compressive stress. The stress balancing film 14 has an internal stress including a stress F14b caused by the growth of crystal grains on the film having a concavo-convex structure and a stress F14a caused by the material, and has only the stress F14a caused by the material. It generates a stronger stress than a thin film. Since this is formed on the upper electrode film 27, the balance between the element stress F12 and the internal stress F14 is ensured. Therefore, the thin film piezoelectric element 12b has a higher stress balancing effect than the conventional one. Thereby, in the thin film piezoelectric element 12b, the balance of stress along the thickness direction inside the element is more reliably ensured.

  In the state where only the element stress F12 is acting, the thin film piezoelectric element 12b warps. However, in the thin film piezoelectric element 12b, the internal stress F14 acts in addition to this, and the balance between both stresses is ensured reliably. Therefore, the warp of the thin film piezoelectric element 12b is sufficiently suppressed. Thus, although the thin film piezoelectric element 12b is a single-layer piezoelectric laminate, its warping can be sufficiently suppressed and bending displacement can be suppressed even when no voltage is applied. Therefore, the thin film piezoelectric element 12b is suitable for HGA.

  Further, since the thin film piezoelectric element 12b includes the lower adhesion film 16a and the upper adhesion film 16b, the adhesion of the lower electrode film 17, the piezoelectric film 13 and the upper electrode film 27 is enhanced. Moreover, the uneven surface 13A of the piezoelectric film 13 has an uneven structure, and the upper adhesive film 16b and the upper electrode film 27 also have an uneven structure similar to this. Then, since the contact area with other films is expanded as compared with the case where each film is flat, the adhesion between the films is further enhanced.

(Head gimbal assembly and hard disk drive)
First, the structure of the HGA related to the present invention will be described with reference to FIGS. 15 to 18 together with FIG. 5 described above. Here, FIG. 15 is a perspective view of the entire HGA 101 related to the present invention as seen from the front side, and FIG. 16 is a perspective view of the main part of the HGA 101 as seen from the front side. FIG. 17 is a perspective view of the main part of the suspension 50 constituting the HGA 101 as viewed from the front side. FIG. 18 is an enlarged perspective view showing a portion where the thin film piezoelectric element 12b of the flexure 106 is fixed.

  The HGA 101 has a suspension 50 and a head slider 60 as shown in FIG. The suspension 50 has a base plate 102, a load beam 103, a flexure 106, and a damper (not shown), and these are joined and integrated by welding or the like.

  The base plate 102 is a component for fixing the suspension 50 to a drive arm 209 of the hard disk device 201 described later, and is formed using a metal such as stainless steel.

  A load beam 103 is fixed to the base plate 102. The load beam 103 has a shape in which the width gradually decreases as the distance from the base plate 102 increases. The load beam 103 has a load bending portion that generates a force for pressing the head slider 60 against a hard disk 202 (to be described later) of the hard disk device 201.

  The flexure 106 includes a flexure substrate 104, a base insulating layer 5, a connection wiring 111, and thin film piezoelectric elements 12a and 12b as shown in FIGS. It has a layer 25. The flexure 106 has a structure in which the base insulating layer 5 is formed on the flexure substrate 104, and the connection wiring 111 and the thin film piezoelectric elements 12a and 12b are fixed thereon. Further, a protective insulating layer 25 is formed so as to cover the connection wiring 111 and the thin film piezoelectric elements 12a and 12b.

  The flexure 106 has a structure with a piezoelectric element which is provided with a piezoelectric element by attaching the thin film piezoelectric elements 12 a and 12 b to the surface of the base insulating layer 5 in addition to the connection wiring 111.

  The flexure 106 has a gimbal portion 110 on the tip side (load beam 103 side). The gimbal portion 110 has a tongue portion 119 on which the head slider 60 is mounted, and a plurality of connection pads 120 are formed on the tip side of the tongue portion 119. The connection pad 120 is electrically connected to an electrode pad (not shown) of the head slider 60.

  The flexure 106 expands and contracts the thin film piezoelectric elements 12 a and 12 b, and accordingly, expands and contracts a stainless steel portion (also referred to as an outrigger portion) that protrudes outside the tongue portion 119. As a result, the position of the head slider 60 moves very slightly around a dimple (not shown), so that minute position control of the head slider 60 is performed.

  The flexure substrate 104 is a substrate that supports the entire flexure 106 and is formed using stainless steel. The back surface is fixed to the base plate 102 and the load beam 103 by welding. As shown in FIG. 15, the flexure substrate 104 has a center portion 104 a that is fixed to the surfaces of the load beam 103 and the base plate 102, and a wiring portion 104 b that extends outward from the base plate 102.

The base insulating layer 5 covers the surface of the flexure substrate 104. The base insulating layer 5 is formed using polyimide, for example, and has a thickness of about 5 μm to 10 μm. In addition, as shown in detail in FIG. 17 , the insulating base layer 5 is divided into two portions on the load beam 103, one of which is the first wiring portion 5a and the other is the second wiring portion 5b. It has become. A thin film piezoelectric element 12a and a thin film piezoelectric element 12b are fixed to the respective surfaces. The upper terminal electrode 19a and the lower terminal electrode 19b described above in the thin film piezoelectric elements 12a and 12b are connected to the electrode pads 118 and 118b. The electrode pads 118 and 118 b are connected to the connection wiring 111.

  A plurality of connection wirings 111 are formed on the respective surfaces of the first wiring part 5a and the second wiring part 5b. Each connection wiring 111 is formed using a conductor such as copper. Each connection wire 111 has one end connected to the thin electrode pads 118 a and 118 b or each connection pad 120.

  The head slider 60 is formed with a thin film magnetic head (not shown) for recording and reproducing data. The head slider 60 is formed with a plurality of electrode pads (not shown), and each electrode pad is connected to the connection pad 120.

Next, with reference to FIG. 19 will be explained in the hard disk drive. FIG. 19 is a perspective view showing a hard disk device 201 including the above-described HGA 101. The hard disk device 201 includes a hard disk (magnetic recording medium) 202 that rotates at high speed and an HGA 101. The hard disk device 201 is a device that operates the HGA 101 to record and reproduce data on the recording surface of the hard disk 202. The hard disk 202 has a plurality of disks (four in the figure). Each disk has a recording surface facing the head slider 60.

  The hard disk device 201 positions the head slider 60 on the track by the assembly carriage device 203. A thin film magnetic head (not shown) is formed on the head slider 60. In addition, the hard disk device 201 has a plurality of drive arms 209. Each drive arm 209 is rotated about a pivot bearing shaft 206 by a voice coil motor (VCM) 205 and stacked in a direction along the pivot bearing shaft 206. An HGA 101 is attached to the tip of each drive arm 209.

  Further, the hard disk device 201 has a control circuit 204 that controls recording and reproduction.

  When the HGA 101 is rotated, the hard disk drive 201 moves the head slider 60 in the radial direction of the hard disk 202, that is, in the direction crossing the track line.

  Since the HGA 101 and the hard disk device 201 are manufactured using the thin film piezoelectric elements 12a and 12b described above, stable position control with high linearity can be performed with respect to a wider range of applied voltages. Further, since the warpage of the thin film piezoelectric elements 12a and 12b is suppressed, the mounting (adhering to the base insulating layer 5) can be easily performed. Further, the displacement in the longitudinal direction can be generated more efficiently than in the case of using a conventional thin film piezoelectric element, and the position of the thin film magnetic head can be adjusted effectively.

(Inkjet head)
Then, with the ink jet head will be described with reference to FIG. 20.

  FIG. 20 is a cross-sectional view illustrating a schematic configuration of the inkjet head 301. The inkjet head 301 is manufactured using thin film piezoelectric elements 312a, 312b, 312c. The inkjet head 301 includes a head main body 302 and thin film piezoelectric elements 312a, 312b, and 312c.

  The head main body 302 has an ink flow path structure 303 and a vibration member 305.

  The ink flow path structure 303 includes a substrate 303A on which a plurality (three in FIG. 20) of nozzles 303a, 303b, and 303c and ink flow paths 304a, 304b, and 304c are formed. A plurality of ink chambers 306a, 306b, and 306c are formed so as to correspond to the flow paths 304a, 304b, and 304c. Each of the ink chambers 306a, 306b, and 306c is partitioned by a side wall portion 307, and each of them communicates with the nozzles 303a, 303b, and 303c via the ink flow paths 304a, 304b, and 304c. Each ink chamber 306a, 306b, 306c stores ink (not shown). The ink flow path structure 303 can be manufactured using various materials such as resin, metal, silicon (Si) substrate, glass substrate, and ceramics.

The vibration member 305 is fixed to the ink flow path structure 303 so as to cover the plurality of ink chambers 306a, 306b, and 306c. The vibration member 305 is made of, for example, silicon oxide (SiO ₂ ) and has a thickness of about 3.5 μm. Thin film piezoelectric elements 312a, 312b, and 312c are fixed to the outside of the vibration member 305 so as to correspond to the ink chambers 306a, 306b, and 306c. The thin film piezoelectric elements 312a, 312b, 312c are fixed to the vibration member 305 using an adhesive 313.

  Each thin film piezoelectric element 312a, 312b, 312c has the same configuration as the thin film piezoelectric element 12b described above. Each thin film piezoelectric element 312a, 312b, 312c has an electrode terminal (not shown). Each electrode terminal is connected to a wiring (not shown).

  The head main body 302 and the inkjet head 301 can be manufactured as follows. First, nozzles 303a, 303b, and 303c and ink flow paths 304a, 304b, and 304c are formed on the substrate 303A by machining. Next, the side wall portion 307 in which the ink chambers 306a, 306b, and 306c are formed by machining or etching is fixed to the substrate 303A. Alternatively, the side wall portion 307 is formed on the substrate 303A by plating. Then, the ink flow path structure 303 is manufactured. Thereafter, when the vibration member 305 is fixed to the ink flow path structure 303, the head main body 302 is manufactured.

Then, the substrate is removed together with the above-described base film 15 by polishing , etching, or the like to manufacture thin film piezoelectric elements 312a, 312b, 312c, and these are fixed to the vibration member 305 using an adhesive 313 such as an epoxy resin. . Then, the inkjet head 301 is manufactured.

  When power is supplied to the thin film piezoelectric elements 312a, 312b, and 312c from the power source (not shown) through the wiring and electrode terminals in the inkjet head 301 manufactured in this way, as shown in FIG. 20, for example, by deformation of the thin film piezoelectric element 312b. The bending portion 305d is formed in the vibration member 305. Then, the ink stored in the ink chambers 306a, 306b, and 306c is pushed out, and the ink is ejected through the ink flow paths 304a, 304b, and 304c and the nozzles 303a, 303b, and 303c.

  Since the thin film piezoelectric elements 312a, 312b, and 312c have a large coercive electric field as in the thin film piezoelectric element 12b described above, the thin film piezoelectric elements 312a, 312b, and 312c operate stably with high linearity with respect to a wider range of applied voltages. Further, since the warpage is suppressed in the same manner as the thin film piezoelectric element 12b described above, the vibration member 305 can be easily fixed.

  In addition, the inkjet head 301 forms a lower electrode film, a piezoelectric film, and an upper electrode film on a silicon substrate as in the prior art, and forms ink channels and nozzles on the silicon substrate by reactive ion etching or the like. Compared to the case, the material restrictions in the head main body 302 are reduced, and various materials can be used for the head main body 302. Therefore, when manufacturing the head main body 302, a method that is less expensive than processing by reactive ion etching or the like can be used, and the inkjet head 301 can be easily manufactured. Although not shown, the inkjet head can be manufactured by manufacturing the nozzle and the ink flow path using different substrates and then bonding them, and then fixing the thin film piezoelectric element. In this case, for example, the nozzle can be manufactured by machining, and the ink flow path can be formed by plating.

(Variable focus lenses)
Next, have One varifocal lens, FIG. 21 will be described with reference to FIG. 22.

FIG. 21 is a plan view showing a schematic configuration of a variable focus lens 401 related to the present invention, and FIG. 22 is a sectional view taken along line 22-22 of FIG. The variable focus lens 401 includes a lens body 410 and two thin film piezoelectric elements 412 and 412.

  The lens body 410 includes a transparent substrate 402, a metallic housing 403, a transparent elastic body 404, a transparent gel-like resin 405, and a metal ring member 406.

  The transparent substrate 402 is made of a transparent member such as glass and is formed in a rectangular shape. The metallic casing 403 is a cylindrical body having a rectangular shape in plan view and having a size along the transparent substrate 402, and the inner side is a cylindrical gap 403a. The metallic housing 403 is formed using, for example, stainless steel. The transparent elastic body 404 is made of a material that is transparent and elastic, such as a transparent polymer, and easily deforms. The transparent elastic body 404 has a cylindrical gap 404a on the inside. The transparent gel-like resin 405 is made of a silicone resin or the like and is stored in the cylindrical gap 404a of the transparent elastic body 404. The transparent gel-like resin 405 has a columnar shape by fitting into the inner wall of the cylindrical gap 404a without a gap. The metal ring member 406 is an annular member having an appropriate thickness, and is placed on the surface of the transparent gel resin 405 in the cylindrical gap 404a.

  The thin film piezoelectric elements 412 and 412 are bridged between the metal ring member 406 and the metallic casing 403 across the transparent elastic body 404, and are fixed to both using an adhesive (not shown). The thin film piezoelectric elements 412 and 412 are arranged on a straight line passing through the center of the transparent gel-like resin 405 so as to face each other with the center therebetween.

  The thin film piezoelectric elements 412 and 412 have the same configuration as the thin film piezoelectric element 12b described above. Each thin film piezoelectric element 412, 412 has an electrode terminal (not shown). Each electrode terminal is connected to a wiring (not shown).

  The variable focus lens 401 having the above-described configuration is manufactured as follows. First, the silicon wafer 2 is removed together with the above-described base film 15 by polishing, etching, or the like, and the thin film piezoelectric elements 412 and 412 are manufactured. When the thin film piezoelectric elements 412 and 412 are fixed to the lens body 410 with an adhesive (not shown), the variable focus lens 401 is manufactured.

  In such a variable focus lens 401, when power is supplied to the thin film piezoelectric elements 412 and 412 through wiring, the thin film piezoelectric elements 412 and 412 are deformed. In response to the deformation, the metal ring member 406 is pushed, whereby the transparent gel-like resin 405 is deformed. In this way, the variable focal length lens 401 can change the focal length. Since the thin film piezoelectric element 412 has a large coercive electric field like the thin film piezoelectric element 12b described above, the thin film piezoelectric element 412 performs a stable operation with high linearity with respect to a wider range of applied voltages. Further, since the warpage is suppressed similarly to the thin film piezoelectric element 12b described above, the lens main body 410 can be easily fixed.

(Modified example of variable focus lens)
Next, a modification of the variable focus lens will be described with reference to FIG. FIG. 23 is a cross-sectional view showing a schematic configuration of a variable focus lens 451 according to a modification. The variable focus lens 451 has a lens body 452 and thin film piezoelectric elements 412 and 412.

  The lens body 452 includes transparent glass substrates 453 and 453, a sealing resin member 454, and a transparent gel resin 455.

  The transparent glass substrates 453 and 453 are formed in a thin plate shape and have moderate elasticity that can be appropriately curved. The transparent glass substrates 453 and 453 are arranged to face each other with a predetermined interval. A sealing resin member 454 is fixed to the entire periphery between the transparent glass substrates 453 and 453. A sealed space 456 is formed by such transparent glass substrates 453 and 453 and the sealing resin member 454, and a transparent gel resin 455 similar to the transparent gel resin 405 is stored therein.

  The thin film piezoelectric elements 412 and 412 are fixed to the outside of one transparent glass substrate 453 using an adhesive (not shown). These thin film piezoelectric elements 412 also have electrode terminals (not shown) as in the variable focus lens 401 described above. A wiring (not shown) is connected to the electrode terminal. When power is supplied to the thin film piezoelectric elements 412 and 412 through this wiring, the thin film piezoelectric elements 412 and 412 are deformed. In response to the deformation, the transparent glass substrate 453 is distorted (or bent), whereby the transparent gel-like resin 455 is deformed. Thus, the variable focal length lens 451 can change the focal length. Also in the variable focus lens 451, since the coercive electric field of the thin film piezoelectric elements 412 and 412 is large like the thin film piezoelectric element 12b described above, stable operation with high linearity with respect to a wider range of applied voltages. I do. Further, since the warpage is suppressed similarly to the thin film piezoelectric element 12b described above, the lens main body 452 can be easily fixed.

(Pulse wave sensor)
Then, with the pulse wave sensor related to the present invention will be described with reference to FIG. 24. FIG. 24 is a cross-sectional view showing a schematic configuration of a pulse wave sensor 501 related to the present invention . The pulse wave sensor 501 includes a sensor main body 502 and a thin film piezoelectric element 512.

  The sensor body 502 includes a metallic housing 504, a sealing member 505, a diaphragm 503 made of a flexible member, a metal pad 507, a wiring member 509, and a lead wire 510.

  The metallic housing 504 is made of a metal such as aluminum or stainless steel. The metallic casing 504 is a bottomed cylindrical member in which a recess 501a is formed in the center and a wall 501b is formed so as to surround the periphery. The sealing member 505 is made of an elastic member such as silicone rubber, and is fixed between the wall portion 501b of the metallic casing 504 and the diaphragm 503. The diaphragm 503 is formed in a disk shape having a diameter of about 10 mm and a thickness of about 0.1 mm. The diaphragm 503 is formed to be deformable using a metal such as stainless steel.

  The metal pad 507 is made of Au, Cr, Cu or the like, and is fixed to the inner side (the recess 501a side) of the vibration plate 503 using an adhesive 506b such as an epoxy resin. The metal pad 507 is connected to the thin film piezoelectric element 512 by a wiring member 509 made of Au or the like. The metal pad 507 is also connected to the lead wire 510 by solder 508. The lead wire 510 is connected to a power source (not shown).

  The thin film piezoelectric element 512 is fixed to the inside of the vibration plate 503 (the recess 501a side) using an adhesive 506a such as an epoxy resin. The thin film piezoelectric element 512 has the same configuration as the thin film piezoelectric element 12b described above. The thin film piezoelectric element 512 is connected to a wiring member 509.

  Such a pulse wave sensor 501 is used as follows. The diaphragm 503 is brought into contact with a human body such as a human arm (not shown). Then, the pulsation of the human body is transmitted to the diaphragm 503, and the diaphragm 503 is deformed. When the diaphragm 503 is deformed, the thin film piezoelectric element 512 is deformed accordingly, and a weak electric signal (pulse wave signal) corresponding to the deformation is output from the thin film piezoelectric element 512. The electric signal is output to the outside through the wiring member 509, the metal pad 507, and the lead wire 510. When this is amplified by an amplifier (not shown), the waveform of the pulse wave signal can be observed. In this way, the pulse wave signal can be detected by the pulse wave sensor 501. Since the thin film piezoelectric element 512 has a large coercive electric field like the thin film piezoelectric element 12b described above, an electric output with high linearity can be obtained for a wider range of inputs. Further, since the warpage is suppressed similarly to the thin film piezoelectric element 12b described above, the vibration member 503 can be easily fixed.

In the above description , the pulse wave sensor is described as an example of the sensor. However, the present invention can be applied to various sensors such as a pressure sensor, a vibration sensor, an acceleration sensor, and a load sensor.

  The above description is the description of the embodiment of the present invention, and does not limit the apparatus and method of the present invention, and various modifications can be easily implemented. In addition, an apparatus or method configured by appropriately combining components, functions, features, or method steps in each embodiment is also included in the present invention.

By applying the present invention, it is possible to obtain a stable piezoelectric characteristic with respect to a wider range of applied voltages, and to perform an operation with excellent linearity with respect to a wider range of applied voltages. The present invention can be used in the fields of a thin film piezoelectric substrate, a thin film piezoelectric element, and a manufacturing method thereof.

  DESCRIPTION OF SYMBOLS 1 ... Thin film piezoelectric substrate, 2 ... Silicon wafer, 3 ... Laminated film, 10 ... Element part, 12a, 12b, 112b, 312a, 312b, 312c, 412, 512 ... Thin film piezoelectric element, 13 ... Piezoelectric film, 13A ... Uneven surface, 14 ... Stress balancing film, 19a ... Lower terminal electrode, 19b ... Upper terminal electrode, 27, 127 ... Upper electrode film, 50 ... Suspension, 60 ... Head slider, 101 ... HGA, 201 ... Hard disk device, 301 ... Inkjet head, 302... Head body, 303 a, 303 b, 303 c... Nozzle, 304 a, 304 b, 304 c .. ink flow path, 306 a, 306 b, 306 c. 405,455 ... transparent gel resin, 501 ... pulse wave sensor, 502 ... sensor body, 03 ... vibration plate.

Claims (10)

A thin film piezoelectric substrate in which a laminated film in which a lower electrode film, a piezoelectric film, and an upper electrode film are sequentially laminated is formed on the surface of a film formation substrate,
The upper surface of the piezoelectric film on the upper electrode film side is an uneven surface having a convex portion and a concave portion, and the convex portion is a curved surface protruding in a convex shape from the center surface in the height direction of the concave and convex surface. And the concave portion is a curved surface following the convex portion recessed in a concave shape from the central surface,
The upper electrode film is formed on the uneven surface,
The piezoelectric film is made of lead zirconate titanate represented by the general formula Pb (Zr _x , Ti _(1-x) ) O ₃ , and x satisfies the condition of 0.53 <x <0.70. And satisfying the following lattice constant conditions concerning the lattice constant dv (unit: nm) in the surface normal direction, and further (100) plane orientation in the surface vertical direction,
The piezoelectric film has a tensile stress;
The laminated film further includes a stress balancing film laminated on the upper electrode film, the stress balancing film including the lower electrode film, the piezoelectric film, and the upper electrode film from the upper electrode film to the lower part. An internal stress that can cancel the element stress that warps in a convex direction toward the electrode film, and is formed on the upper electrode film so as to ensure a balance between the element stress and the internal stress;
The upper electrode film has a film thickness such that at least a part from the lower surface on the uneven surface side to the upper surface on the stress balancing film side enters the recess,
The upper top surface of the stress balancing layer side of the electrode film is an uneven surface corresponding to the uneven surface of the piezoelectric film, the upper electrode film thin film in which the stress balancing layer on the top surface is formed of Piezoelectric substrate.
dv> 0.02x + 0.398 A thin film piezoelectric substrate in which a laminated film in which a lower electrode film, a piezoelectric film, and an upper electrode film are sequentially laminated is formed on the surface of a film formation substrate,
The upper surface of the piezoelectric film on the upper electrode film side is an uneven surface having a convex portion and a concave portion, and the convex portion is a curved surface protruding in a convex shape from the center surface in the height direction of the concave and convex surface. And the concave portion is a curved surface following the convex portion recessed in a concave shape from the central surface,
The upper electrode film is formed on the uneven surface,
The piezoelectric film is made of lead zirconate titanate represented by the general formula Pb (Zr _x , Ti _(1-x) ) O ₃ , and x satisfies the condition of 0.53 <x <0.70. And satisfying the following lattice constant conditions concerning the lattice constant dv (unit: nm) in the surface normal direction, and further (100) plane orientation in the surface vertical direction,
The piezoelectric film is an epitaxial film formed by epitaxial growth, has a film thickness larger than 3 μm, and has a rhombohedral crystal structure.
The upper adhesive film further includes an upper adhesive film formed on the uneven surface of the piezoelectric film, and the upper adhesive film has at least a half portion from the lower surface on the uneven surface side to the upper surface on the upper electrode film side. thin film piezoelectric substrate having a degree of thickness entering the.
dv> 0.02x + 0.398 The piezoelectric film is an epitaxial film formed by epitaxial growth, has a film thickness larger than 3 μm, and has a rhombohedral crystal structure.
The upper adhesive film further includes an upper adhesive film formed on the uneven surface of the piezoelectric film, and the upper adhesive film has at least a half portion from the lower surface on the uneven surface side to the upper surface on the upper electrode film side. thin film piezoelectric substrate of claim 1 having a thickness that enters. The thin film piezoelectric substrate according to claim 1 , wherein the piezoelectric film has a coercive electric field larger than 20V. From the thin film piezoelectric substrate in which the lower electrode film, the piezoelectric film, and the upper electrode film are sequentially laminated, and the laminated film in which a plurality of element portions are formed is formed on the surface of the film formation substrate, the film formation substrate Is a thin film piezoelectric element manufactured using each of the element portions after being removed ,
The upper surface of the piezoelectric film on the upper electrode film side is an uneven surface having a convex portion and a concave portion, and the convex portion is a curved surface protruding in a convex shape from the center surface in the height direction of the concave and convex surface. And the concave portion is a curved surface following the convex portion recessed in a concave shape from the central surface,
The upper electrode film is formed on the uneven surface,
The piezoelectric film is made of lead zirconate titanate represented by the general formula Pb (Zr _x , Ti _(1-x) ) O ₃ , and x satisfies the condition of 0.53 <x <0.70. And satisfying the following lattice constant conditions concerning the lattice constant dv (unit: nm) in the surface normal direction, and further (100) plane orientation in the surface vertical direction,
The element portion has an upper terminal electrode connected to the upper electrode film, and a lower terminal electrode connected to the lower electrode film,
The piezoelectric film has a tensile stress;
The laminated film further includes a stress balancing film laminated on the upper electrode film, the stress balancing film including the lower electrode film, the piezoelectric film, and the upper electrode film from the upper electrode film to the lower part. An internal stress that can cancel the element stress that warps in a convex direction toward the electrode film, and is formed on the upper electrode film so as to ensure a balance between the element stress and the internal stress;
The upper electrode film has a film thickness such that at least a part from the lower surface on the uneven surface side to the upper surface on the stress balancing film side enters the recess,
The upper top surface of the stress balancing layer side of the electrode film is an uneven surface corresponding to the uneven surface of the piezoelectric film, the upper electrode film thin film in which the stress balancing layer on the top surface is formed of Piezoelectric element.
dv> 0.02x + 0.398 From the thin film piezoelectric substrate in which the lower electrode film, the piezoelectric film, and the upper electrode film are sequentially laminated, and the laminated film in which a plurality of element portions are formed is formed on the surface of the film formation substrate, the film formation substrate Is a thin film piezoelectric element manufactured using each of the element portions after being removed,
The upper surface of the piezoelectric film on the upper electrode film side is an uneven surface having a convex portion and a concave portion, and the convex portion is a curved surface protruding in a convex shape from the center surface in the height direction of the concave and convex surface. And the concave portion is a curved surface following the convex portion recessed in a concave shape from the central surface,
The upper electrode film is formed on the uneven surface,
The piezoelectric film is made of lead zirconate titanate represented by the general formula Pb (Zr _x , Ti _(1-x) ) O ₃ , and x satisfies the condition of 0.53 <x <0.70. And satisfying the following lattice constant condition concerning the lattice constant dv (unit: nm) in the surface normal direction, and further (100) plane orientation in the surface vertical direction,
The element portion has an upper terminal electrode connected to the upper electrode film, and a lower terminal electrode connected to the lower electrode film,
The piezoelectric film is an epitaxial film formed by epitaxial growth, has a film thickness larger than 3 μm, and has a rhombohedral crystal structure.
The upper adhesive film further includes an upper adhesive film formed on the uneven surface of the piezoelectric film, and the upper adhesive film has at least a half portion from the lower surface on the uneven surface side to the upper surface on the upper electrode film side. thin film piezoelectric element having a degree of thickness entering the.
dv> 0.02x + 0.398 The piezoelectric film is an epitaxial film formed by epitaxial growth, has a film thickness larger than 3 μm, and has a rhombohedral crystal structure.
The upper adhesive film further includes an upper adhesive film formed on the uneven surface of the piezoelectric film, and the upper adhesive film has at least a half portion from the lower surface on the uneven surface side to the upper surface on the upper electrode film side. thin film piezoelectric element according to claim 5, further comprising a thickness that enters. The thin film piezoelectric element according to claim 5 , wherein the piezoelectric film has a coercive electric field larger than 20V. A laminated film forming step in which a laminated film in which a lower electrode film, a piezoelectric film and an upper electrode film are laminated in order is formed on the surfaces of a plurality of deposition substrates;
An element part forming step of forming a plurality of element parts in the laminated film by etching the laminated film;
An electrode forming step of forming a lower terminal electrode and an upper terminal electrode on the lower electrode film and the upper electrode film, respectively, in each element portion;
The laminated film forming step includes a measurement step of measuring a diffraction angle of a diffraction intensity peak on a (002) plane by an X-ray diffraction method for the plurality of film formation substrates,
Lattice constant condition conformance that satisfies the following lattice constant condition regarding the lattice constant dv (unit: nm) in the surface vertical direction obtained based on the diffraction angle obtained by the measurement step among the plurality of film forming substrates. A method for manufacturing a thin film piezoelectric element using a substrate.
dv> 0.02x + 0.398 An insulating substrate manufacturing process for manufacturing an insulating substrate having an insulating film formed on the surface of the substrate;
A substrate laminating step of laminating the deposition substrate and the insulating substrate such that the insulating film and the upper electrode film are opposed to each other;
A substrate removing step of removing either the insulating substrate or the film-forming substrate of the laminated substrates laminated by the substrate laminating step;
The method for manufacturing a thin film piezoelectric element according to claim 9, wherein the element part forming step is executed after the substrate removing step.